// Formatting library for C++ - std::ostream support
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_OSTREAM_H_
#define FMT_OSTREAM_H_

#include "format.h"
#include <ostream>

FMT_BEGIN_NAMESPACE
namespace internal {

template <class Char>
class formatbuf : public std::basic_streambuf<Char> {
  private:
    typedef typename std::basic_streambuf<Char>::int_type int_type;
    typedef typename std::basic_streambuf<Char>::traits_type traits_type;

    basic_buffer<Char>& buffer_;

  public:
    formatbuf(basic_buffer<Char>& buffer) : buffer_(buffer) {}

  protected:
    // The put-area is actually always empty. This makes the implementation
    // simpler and has the advantage that the streambuf and the buffer are
    // always in sync and sputc never writes into uninitialized memory. The
    // obvious disadvantage is that each call to sputc always results in a
    // (virtual) call to overflow. There is no disadvantage here for sputn since
    // this always results in a call to xsputn.

    int_type overflow(int_type ch = traits_type::eof()) FMT_OVERRIDE {
        if (!traits_type::eq_int_type(ch, traits_type::eof()))
            buffer_.push_back(static_cast<Char>(ch));
        return ch;
    }

    std::streamsize xsputn(const Char* s, std::streamsize count) FMT_OVERRIDE {
        buffer_.append(s, s + count);
        return count;
    }
};

template <typename Char>
struct test_stream : std::basic_ostream<Char> {
  private:
    struct null;
    // Hide all operator<< from std::basic_ostream<Char>.
    void operator<<(null);
};

// Checks if T has a user-defined operator<< (e.g. not a member of
// std::ostream).
template <typename T, typename Char>
class is_streamable {
  private:
    template <typename U>
    static decltype(internal::declval<test_stream<Char>&>()
                        << internal::declval<U>(),
                    std::true_type())
    test(int);

    template <typename>
    static std::false_type test(...);

    typedef decltype(test<T>(0)) result;

  public:
    static const bool value = result::value;
};

// Write the content of buf to os.
template <typename Char>
void write(std::basic_ostream<Char>& os, basic_buffer<Char>& buf) {
    const Char* data = buf.data();
    typedef std::make_unsigned<std::streamsize>::type UnsignedStreamSize;
    UnsignedStreamSize size = buf.size();
    UnsignedStreamSize max_size =
        internal::to_unsigned((std::numeric_limits<std::streamsize>::max)());
    do {
        UnsignedStreamSize n = size <= max_size ? size : max_size;
        os.write(data, static_cast<std::streamsize>(n));
        data += n;
        size -= n;
    } while (size != 0);
}

template <typename Char, typename T>
void format_value(basic_buffer<Char>& buffer, const T& value) {
    internal::formatbuf<Char> format_buf(buffer);
    std::basic_ostream<Char> output(&format_buf);
    output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
    output << value;
    buffer.resize(buffer.size());
}
} // namespace internal

// Disable conversion to int if T has an overloaded operator<< which is a free
// function (not a member of std::ostream).
template <typename T, typename Char>
struct convert_to_int<T, Char, void> {
    static const bool value = convert_to_int<T, Char, int>::value &&
                              !internal::is_streamable<T, Char>::value;
};

// Formats an object of type T that has an overloaded ostream operator<<.
template <typename T, typename Char>
struct formatter<T, Char,
                 typename std::enable_if<
                     internal::is_streamable<T, Char>::value &&
                     !internal::format_type<typename buffer_context<Char>::type,
                                            T>::value>::type>
    : formatter<basic_string_view<Char>, Char> {

    template <typename Context>
    auto format(const T& value, Context& ctx) -> decltype(ctx.out()) {
        basic_memory_buffer<Char> buffer;
        internal::format_value(buffer, value);
        basic_string_view<Char> str(buffer.data(), buffer.size());
        return formatter<basic_string_view<Char>, Char>::format(str, ctx);
    }
};

template <typename Char>
inline void
vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
       basic_format_args<typename buffer_context<Char>::type> args) {
    basic_memory_buffer<Char> buffer;
    internal::vformat_to(buffer, format_str, args);
    internal::write(os, buffer);
}
/**
  \rst
  Prints formatted data to the stream *os*.

  **Example**::

    fmt::print(cerr, "Don't {}!", "panic");
  \endrst
 */
template <typename S, typename... Args>
inline typename std::enable_if<internal::is_string<S>::value>::type
print(std::basic_ostream<FMT_CHAR(S)>& os, const S& format_str,
      const Args&... args) {
    internal::checked_args<S, Args...> ca(format_str, args...);
    vprint(os, to_string_view(format_str), *ca);
}
FMT_END_NAMESPACE

#endif // FMT_OSTREAM_H_
